5 replies to this topic

[David Southall]

I would say 'increase'.

I'm not overly-familiar with plate heat exchangers (I'm more familiar with plate-fins), but as I understand it there are a given number of plates for the 'hot' fluid and a given number of plates for the 'cold' fluid. The cold fluid flows through the cold layers in a parallel type arrangement, same for the hot fluid. The hot fluid layers are typically laid counter-current to the cold layers.

By removing plates, you will effectively be reducing the free flow area. This will increase the velocity, which is proportional to the square root of the pressure drop, so I would anticipate an increase in pressure drop. You could very roughly estimate the increase by scaling like this. For example, if you reduce the number of layers by 10%, the free flow area will be reduced by roughly 10%, so the velocity will increase by roughly 10%, meaning the pressure drop across the plate will increase by roughly 5%.

This doesn't allow for heat transfer performance, which will also change. You could perhaps ask the original exchanger vendor to re-rate the exchanger for you (I've done this before).

[Pronab]

Pressure drop will increase.
This is a very old issue. However what about thermal issue?

[paulo]

I agree with pronab. Pressure drop will increase and depending on the fouling factor or safety margin of the plate heat exchanger the process conditions will not be achieved anymore.

[esads]

Removing the plates reduces the volume... the pressure drop will therefore increase.
If someone has some formula examples to calculate the pressure drop in plate heat exchanger (what ever the number of plates) please send it to esads@bih.net.ba.... thanks